The Edmonton Oilers scored 2 short-handed goals on San Jose Sharks during the 2nd game of the first round 16-17 playoffs. Even though a team on a powerplay has one more skater than the other team, if a team is experiencing what the Sharks did, not accepting a penalty wouldn't be crazy idea to consider.
So although there isn't any true upside to rejecting a penalty, is it possible for a team to reject a power play?
No. Penalties are awarded by the officials. Team preference is not a factor; they do not have any input on the decision.
Rule 15.1, page 25 of the NHL rulebook makes clear that
[if the offender's team has possession] the Referee shall immediately blow his whistle and penalise the offending player.
[after a delayed penalty, and the offender's team gains possession], the Referee will blow his whistle to stop play and impose the penalty on the offending player.
Minor penalties may also be washed put automatically if a delayed penalty leads to a goal by the non-offending team, but this is an artifact of the normal rule applying to delayed penalties.
At no point in any part of the rule is any mention or implication that the offender's opponents may decide the penalty is not served at all.
